Ultra-Creamy Spinach and Mushroom Lasagna

Ingredients

• 8 tablespoons unsalted butter, plus more for greasing baking dish, divided
• 3 medium cloves garlic, minced
• 2 pounds washed fresh spinach leaves, roughly chopped
• 1 pint heavy cream, divided
• 1/2 teaspoon freshly grated nutmeg
• Kosher salt and freshly ground black pepper
• 1 pound cottage cheese
• 1/2 cup chopped fresh parsley leaves, divided
• 1 egg
• 1 package no-boil lasagna noodles
• 24 ounces button, cremini, or shiitake mushrooms, stems removed, finely chopped
• 2 medium shallots, finely chopped
• 2 teaspoons minced fresh thyme leaves
• 1 tablespoon soy sauce
• 2 teaspoons fresh juice from 1 lemon
• 2 tablespoons flour
• 2 cups whole milk
• 12 ounces whole milk mozzarella, grated, divided
• 2 ounces Parmiggiano-reggiano, grated

Directions

1. Set a rack in the upper-middle position and heat the oven to 400 degrees F. In a large saucepan set over medium-high heat, melt 3 tablespoons butter until the bubbling calms down. Stir in the garlic and cook for about 30 seconds, just until it smells fragrant. Add the spinach by the handful, letting each addition collapse before the next goes in. When all the spinach is in the pot, stir in 1 cup heavy cream. Bring it to a boil, lower it to a lively simmer, and cook for about 15 minutes, stirring often, until thickened and reduced. Mix in the nutmeg, then add salt and pepper until it tastes right.
2. As the spinach cooks, put the cottage cheese, egg, and 6 tablespoons parsley in a food processor. Pulse for about 5 seconds, until the mixture comes together and the cottage cheese curds look more like ricotta.
3. Scrape the cooked spinach mixture into a large bowl with the cottage cheese mixture and stir them together. At the same time, place the lasagna noodles in an 8- by 13-inch baking dish and pour warm water over them. Soak for about 15 minutes, swishing them around now and then so they do not stick. Move the noodles to a clean kitchen towel in one layer so they can dry.
4. While the noodles soak, clean the spinach pot and put it back over medium-high heat. Add 3 more tablespoons butter and let it melt. Stir in the mushrooms and cook for about 10 minutes, stirring now and then, until their moisture has cooked off and they begin to sizzle. Add the shallots and thyme, and cook for about 2 minutes, stirring often, until softened and aromatic. Stir in the soy sauce and lemon juice, then add the remaining heavy cream. Bring the mixture to a simmer and cook for about 3 minutes, until lightly thickened. Add salt and pepper to taste, then scrape the mushrooms into a separate bowl.
5. Clean the pot once more and return it to medium-high heat. Melt the remaining 2 tablespoons butter, then whisk in the flour and cook, whisking the whole time, until it turns a light golden blond. Whisk as you gradually add the milk. Bring the sauce to a simmer, then take it off the heat. Stir in 2/3rds of the mozzarella and the parmesan, then season with salt and pepper to taste.
6. For assembly, dry the 8- by 13-inch baking dish, then butter it. Spread 1 cup cheese sauce across the bottom. Arrange 3 noodles over the sauce, spacing them evenly; there will be about a 1/4-inch gap between the noodles and along the pan edges, and that is fine. Spoon 1/2 of the mushroom mixture evenly over the noodles, then add another 3 noodles. Spread 1/2 of the spinach and cottage cheese mixture over that, followed by another 3 noodles. Add the remaining mushroom mixture, 3 more noodles, the remaining spinach mixture, and a final layer of noodles. Cover the top with the rest of the cheese sauce, smoothing it out evenly. Sprinkle the remaining 1/3rd of the grated mozzarella over the top.
7. Bake for about 20 minutes, until the edges are bubbling. Turn on the broiler and broil for about 5 minutes longer, until the top is lightly browned; if your broiler is underneath the oven, move the lasagna there after baking. Cool the lasagna for 10 minutes before slicing and serving.